The present invention concerns a sealing ring intended upon mounting to be inserted in an axial open annular groove in a first rotor part of a centrifugal separator, which has a second rotor part movable relative to the first rotor part, the second rotor part having a abutment surface intended to be brought in and out of sealing abutment against a sealing surface of a sealing ring mounted in the groove, the sealing ring being pressed axially in a direction into the groove.
In U.S. Pat. No. 4,534,570 a sealing ring of this kind is disclosed, which is exposed to very high loads. To be able during operation to prevent liquid from leaking out of the centrifugal separator passing the sealing ring, the second rotor part has to be pressed with its abutment surface against the sealing surface with a force, which gives a sealing pressure, which with enough margin exceeds the liquid pressure, against which the sealing ring must seal.
The liquid pressure next to sealing rings of this kind in centrifugal separators is often very high as a result of the high number of revolutions per minute at which rotors of centrifugal separators rotate. Therefore, the force needed for tightening the rotor components against the seal often is very high.
It is then very important to ensure that the sealing ring is firmly fixed in its groove after every axial movement of the second rotor part in and out of sealing abutment against the sealing surface of the sealing ring.
For this purpose sealing rings of this kind have conical radial delimiting surfaces and are pressed into annular grooves in the first rotor part, which also has conical delimiting surfaces.
However, this means that a very great portion of the tightening force is taken up by the conical surfaces, which causes high concentrations of stresses in adjacent portions of the first rotor part.
The object of the present invention is to provide a sealing ring which can be kept in its groove in the first rotor part without causing high stresses in adjacent portions of the first rotor part.
The present invention overcomes the drawbacks associated with the prior art by the fact
that the sealing ring of the present invention has a first annular portion turned towards the second rotor part, the first annular portion in unloaded condition having an outer radius, which at least is as large as the outer radius of a first annular portion of the groove, which is arranged to receive this first annular portion of the sealing ring,
that the first annular portion of the sealing ring has a radial width, which at least is as large as the radial width of a section of the first annular portion of the groove located closest to the second rotor part,
that the groove has a second annular portion turned away from the second rotor part, the second annular portion connecting to an axial end of the first annular portion of the groove and having an outer annular recess, which extends axially from this axial end radially outwardly from the outer radius of the first portion at this axial end,
that the groove has a bottom located in the second annular portion of the groove at its end turned away from the second portion of the rotor, that the sealing ring has a second annular portion turned away from the second rotor part, the second annular portion connecting to an axial end of the first annular portion of the sealing ring and having at least one projection, which at least partly fills up the outer annular recess in the second annular portion of the groove and abuts at least against an inner surface of the recess located closest to this axial end, the axial end of the first annular portion of the sealing ring and the axial end of the first annular portion of the groove being located at substantially the same axial level,
that the groove also has an inner annular recess, which extends axially from the bottom of the groove to said section and radially inwardly from the inner radius of the section at an end of the section turned away from the second rotor part, the sealing ring in mounted condition being located radially outside the inner annular recess, and
that the inner annular recess is adapted, upon elastical deformation of at least one of the first rotor part, the first annular portion of the sealing ring and the second annular portion of the sealing ring, to enable the sealing ring to be turned in an inclined position in an axial crossection to an insertion and removal direction, the maximum dimension perpendicular to this insertion and removal direction of the sealing ring being less than the minimum dimension of the groove perpendicular to this insertion and removal direction.
Hereby, the retaining force is accomplished by means of locking by shape instead of by means of a clamping joint and the tightening force is transferred from the sealing ring to the first rotor part by pressing the sealing ring against the bottom of the groove, which causes much lower stress concentrations.
In a preferred embodiment the first and the second annular portion of the sealing ring are formed in one single integrated piece. The projection on the second annular portion of the sealing ring suitably extends substantially along the entire periphery of the sealing ring.
In another embodiment of the invention the radial width of said section decreases by distance from the second rotor part. Hereby, liquid and other pollutants can be prevented from leaking into the groove.
The rotor parts are rotatable around a rotational axis, the sealing ring extending concentrically around the rotational axis.
In a further embodiment of the invention the sealing ring is made of a polymer such as polyetheretherketone or polyoxymethylene.